A disk array apparatus is constituted by a control unit for controlling data input/output to/from the disk array apparatus and a disk formed from a plurality of physical disks for storing the data. Further, the disk array apparatus manages the plurality of physical disks using a RAID (Redundant Array of Independent/Inexpensive Disks) system.
In this type of disk array apparatus, when a fault occurs in one of the plurality of physical disks, the faulty physical disk can be restored using the remaining physical disks. The time required for the physical disk to become usable by an external unit increases in proportion to a storage capacity of the physical disk, and therefore a technique for shortening the time required for the physical disk to become usable is much needed. In recent years, various methods of shortening the time required for a faulty physical disk to become usable have been proposed.
When a fault occurs in a physical disk, as described above, the disk array apparatus cannot determine an unused area (free area) of the physical disk, and therefore a large amount of time is required for the physical disk to become usable by an external unit. Further, when a problem occurs in a restoration source physical disk during restoration of the physical disk, a media error occurs, and in this case, certain data cannot be read from the restoration source physical disk. As a result, the disk array apparatus cannot determine whether the unreadable area is a used area or an unused area, and must therefore reconstruct the area.
Meanwhile, in the proposed related art, data recovery is performed in relation to the used area of the faulty physical disk, but the unused area of the faulty physical disk is not mentioned in detail.
Patent document 1: Japanese Unexamined Patent Publication No. 2002-222063.
Patent document 2: Japanese Unexamined Patent Publication No. H11-24849.